Low Voltage Transformers - Part 1: General Requirements

Low Voltage Transformers - Part 1: General Requirements

1 Scope

1.1 These requirements cover the following types of transformers:

a)    Air-cooled transformers and reactors for general use;

b)    General purpose autotransformers;

c)    Ferroresonant transformers;

d)    Class 2 and Class 3 transformers (which are evaluated in accordance with Part 3);

e)    Cord-connected transformers (which are evaluated in accordance with Part 2);

f)    Transformers incorporating overcurrent or over-temperature protective devices, transient voltage surge protectors, or capacitors; and

g)    Permanently-connected transformers.

1.2 These transformers are intended to be used in accordance with the National Electrical Code, ANSI/NFPA 70, or CSA C22.1, the Canadian Electrical Code, Part I. The Canadian Electrical Code defines low voltage as any voltage from 31 to 750 V inclusive and high voltage as any voltage above 750 V. The National Electrical Code, ANSI/NFPA 70, defines low voltage as any voltage up to 600 V, nominal. Therefore, low voltage transformers intended for use in Canada may be rated above 600 V up to 750 V. Low voltage transformers intended for use in the United States are rated up to 600 V. Where information in clauses and tables in this standard reference voltage ranges, the limit of 600 V applies in the United States, while the limit of 750 V applies in Canada.